HOUSTON — December 12, 2011 — Young infants and toddlers with sickle cell anemia who received the drug hydroxyurea were no more likely to have cellular genetic damage than those who received a placebo or inactive medicine, said researchers from Baylor College of Medicine in Houston and St. Jude Children’s Research Hospital in Memphis, Tenn., yesterday at the American Society of Hematology’s annual meeting in San Diego, Calif.

These findings provide further evidence of the safety of hydroxyurea for children with sickle cell anemia, said the study’s lead author Dr. Patrick T. McGann, a clinical fellow of pediatric hematology and oncology at BCM and the Texas Children’s Hematology Center. There is some concern that hydroxyurea therapy would lead to genetic damage at the cellular level and could increase the risk of developing cancer.

Inherited blood disorder

Sickle cell anemia is an inherited blood disorder caused by a gene mutation in the beta-globin gene. The red blood cells of individuals affected with the disorder are shaped like a sickle or crescent, unlike normal red blood cells that are disc–shaped. Normal, healthy red blood cells move through blood vessels easily, carrying hemoglobin, the critical protein necessary for the delivery of oxygen, throughout the body. The stiff, sickle-shaped red blood cells do not flow as easily and often get stuck in small blood vessels, decreasing oxygen delivery to legs, arms and other organs and resulting in severe pain, increased risk of infection and chronic organ damage.

Hydroxyurea was approved by the U.S. Food and Drug Administration as a treatment for adults with sickle cell disease in 1998, but it has not yet been approved for use in children. Hydroxyurea reduces the amount of sickle hemoglobin by stimulating the production of fetal hemoglobin, which results in healthier red blood cells and a reduction in the frequency and severity of the complications associated with the disorder.

“It is important to demonstrate the low genotoxic risks associated with hydroxyurea for children with sickle cell anemia given that hydroxyurea was historically used as a chemotherapeutic treatment for cancer,” said McGann.

The research team used data collected from the Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG), a multi-center study whose primary goal was to investigate the ability of hydroxyurea to prevent chronic organ damage in very young patients with sickle cell anemia.

A total of 193 infants (average 13.6 months) were assigned at random to receive hydroxyurea or placebo for two years. After studying the effect of the drug, the researchers found no evidence of increased genetic damage in the children who received hydroxyurea than in those who received placebo.

Effective treatment

“We found that young children treated with hydroxyurea for two years did not demonstrate evidence of increased DNA damage when compared to children receiving placebo” said McGann. “These data represent another important piece of evidence that this very effective treatment is safe for young children.”

Other investigators at BCM who contributed to this study include Dr. Jonathan Flanagan, assistant professor of pediatrics at BCM and Thad Howard.

Other investigators include Dr. Stephen Dertinger of Litron Laboratories in Rochester, New York; Dr. Jin He of St. Jude Children’s Research Hospital in Memphis, Tenn.; Dr. Anita Kulharya of the Georgia Health Sciences University in Augusta and Dr. Bruce Thompson of Clinical Trials and Surveys Corp. in Owings Mills, M.D.

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As an international leader in pediatric cancer research and treatment, Texas Children’s Cancer and Hematology Centers are joint programs of Texas Children's Hospital and Baylor College of Medicine. The Centers are dedicated to providing novel therapies and family-centered care to children from infancy through young adulthood with cancer and blood disorders – from the most common to very rare. Texas Children’s Cancer Center is the pediatric program of BCM’s NCI-designated Dan L. Duncan Cancer Center.
Ranked by U.S. News & World Report as the #2 Center in the United States, Texas Children’s Cancer and Hematology Centers treats more childhood cancer and hematology patients than any other program in the U.S., with patients coming from 35 states and 26 countries around the world.